Current-collecting device



April .27 1926.

j C. F. WAGNER CURRENT COLLECTING DEVICE Filed Jul' 5, 1922 INVENTOR Charles F Wa3nen wnmzssss; 4%. M

- ATTORNEY I Patented Apr. 27, 1926.

Uta-21 E?) stares CHARLES F. WAGNER, or rrrrsia'unsrt,

PEBTNSYLVANIA, ASSIGNGR '10 "WESTING- VANIA.

'Application filed July 5,

To all whom it may concern:

Be it known that l, CHE-muesli. acuna,

a citizen of the United States, and av resident ot Pittsburghfin the coun'tyot' Allegheny 5 and'State ot Pennsylvania, have invented a new and us'etul Improvement in Current- Collecting Devices, i of which the following is a specification.

My invention relates to current-collecting devices and ithas particular relation to current equalizing means for brush holder stands.

l-I'eretofore, it-*has been observed that the current collecting b'riishes of dynamo-electric machines, and par ic ularly machines of the rotary converter type which employ a large number of brushes connected in parallelrelation and-which co-op'erate with a single collector ring, are subjected tounequal wear. Extensive experiments have," therefore, been conductedwith a view of determining the cause of the inequality in brush wear.

As aresultot the experiments, it hasbeen ascertained that one of the principal causes of the unequal b'ruslr wear is the uncqu'al flow of current through the variousbrush memberswhicl'i causes the decomposition of the brushes subject to excess current tloW. The inequality of current'tlow in the different brushes may be"attribute'd to several causes, such as the tormation ot a film -of air, of substantially wedge shape, between 'a brush member and the collector ring; a carbon deposit on the contactsurtace ot'cer tain brushes; unequal pressure exerted by the brush springs; uneven contact surfaces of the brushes; inequalities in'the chemical constituents of the contact surfaces, and particularly those of the brush members; the unstable volt-ampere characteristics of brushes in general and the ellect of nonuniform external conditions, such as the resistance and ther'eactauce of the paths of the current from the brushes, as inthe brush holder stand to which the brush shunts are electrically connected.

The cause of the last-mentioned difiiculty is that it has been heretofore customary to construct thebrush holder stands or siclzles inthe form of vertmalty-extending arcuate pedestals of relatively large cross-sectional area and which were mounted at their lower extremities upon suitable trame structures provided for that "purpose. The brush CURRENT-COLLECTING nnv'roia;

1922. Serial No. 572,916.

holders were mounted upon the stands-at 5 spaced intervals throughout the entire length thereof and the conductors which conveyed Clll'l'GnblO or-away from the'machine were. electrically connected to the lower-portion ot the stand adjacent'to the point of attachment to the supporting structure.

T By reason of this construction, the current from the various brushes traversed paths of different lengths through; the stand to the conductor with the result that current rear the various brushes SillfGIGClVOltEIQG drops of dilterent values in the stand according to the proximity or remoteness of the brushes relatively to the conductor. Forexttniple, the current from a bruslr'locatechat "the'upper end or the stand traverseda pathfot greater distance F and, consequently, higher re'sistance, through the stand before entering the conductor than the current tronra brush situatedat a lowerposition on the stand.

One object of myinvention is to overcome the disadvantage encountered by the vbltage drop'in the brushholder stand andto lessen the distance of the current paths therethrouglnby providing a plurality ofc'onductors which are electrically connected to the stand at equally spaced distances and which are adapted to convey 'current'to or away from asingle brush or agroup" ot'adjacent brushes. i

Another objectot the invention is to provide a device of .the character described, which embodies magnetic means embracing the stand between groups of alternating current brusheswhich' is adapted to develop an impedance tending to prevent the cur rent from the various. groups from traversing the path through the -stand and to cause it to flow in the conductor provided for the particular group, whereby the current from each ot the brushes or groups of brushes would be compelled to traverse paths ofsubstanti'ally equal impedance. i

A further object of my invention is to pro vide a simple and eliicient dampingmeinher that may be quickly and easily mounted upon a brush holder stand for the purposes above set forth.

In the accompanying drawing:

Figure 1 is an end elevational view of a -portion of a rotary converter and illustrating a plurality of brush holder stands protially collected the same.

vided with a damping member constructed and arranged in accordance with my invention.

Fig. 2 is a fragmentary elevational View, on a larger scale, of one of the clamping members illustrated in Fig. 1.

Fig. 8 is a. horizontal sectional view through a brush holder stand illustrating the damping member in elevation. I

Referring to the drawing, a portion of a dynamo-electric macl'iine, of the rotary converter type, is illustrated as comprising a base portion 1 upon which a plurality of arcuate brush holder stands or sickles 2 are mounted. Each of ti e stands is provided with a plurality of outwardly extending studs 3 upon which brush holders 4, only two sets of which are illustrated, are mounted for cooperation with a collector ring 5. Conductors 6 connect the studs Sin parallel to a common conductor 7.

The conductors 6 are, however, of greater resistance than the stands 2 by reason of their relatively small cross-sectional area. There is, therefore, a tendency for a greater part of the current to traverse the stand to the lowermost conductor 6 and result in the disadvantage mentioned, rather than to divide equally between the conductors. In order, therefore, to avoid this tendency and to cause an equal amount of current to traverse the conductors 6 and encounter an equal resistance, a. plurality of magnetizable members or damping elements 8 are pro vided which embrace the stands 2 at spaced intervals between groups of the studs 3 and the brush holders 4 carried thereby. Each of the members 8 preferably consists of a pluraliity of laminations 9 which are clamped between bracket members 10 suitably secured to the stands 2.

By means of the abovedescribed construction, the alternating current collected by the brushes of each group traverses the portion of the stands bounded by the members 8 and through the conductors 6 to the common conductor 7. If any alternating current flows from one group of brushes through one'of the stands and past one of the memhere 8 to the portion of the stand which supports an adjacent group of brushes, a strong alternating magnetic flux will be established in the magnetic damping member 8 disposed between the groups, thus producing an impedance to such flow and causing most of the current totraverse the conductor pro-- vided for the group of brushes which ini- Current is thus taken from the stands at spaced intervals throughout its entire length and is prevented from traversing the same for any appreciable distance and resulting in the voltage drop incidental thereto.

I claim as my invention:

1. A current-collecting device comprisinga rotatable contact member, a plurality of brush members cooperating therewith, a common support for said brush members and means associated with said support and disposed between certain of said brush members for offering an impedance to the flow of varying currents through said support from the portion thereof which supports one of the brush members to a portion which sup rotatable contact member, a conductor forv each of the groups of brushes and means for equalizing the flow of current in said conductors.

4. A current-collecting device comprising a brush holder stand, a plurality of brush members-carried thereby and electrically connected in groups for co-operation with a rotatable contact member, a conductor for each of the groups of brush members, means tending to equalize the flow of Variable currents in said conductors by hinder ing the varying current traversing the portion of the stand'which supports the respective groups of brush members from flowing to the portion of the stand which supports another of said groups.

5. A current-collecting device comprising a brush holder stand, a plurality of brushes carried thereby for co-operating with a rotatable contact member and a plurality of conductors electrically connected to said stand at spaced intervals through the length thereof and means adapted to substantially equalize the currents path in said conductors.

6. A current-collecting device comprising a brush holder stand, a plurality of brushes carried thereby for co-operating with a rotatable contact member, a plurality of con-- ductors electrically connected to said stand at spaced intervals through the length there of and magnetizable means embracing said stand between the points of attachment of said conductors.

7. A current-collecting device comprising a collector ring, a plurality of brush members co-operating therewith, a common conducting supporting member, studs on said supporting member conduct-ively supporting said brush members, and means including a magnetizable member associated with said supporting member between two adjacent studs for substantially preventing the flow of alternating current through said supporting member from one of said studs to the other.

8. A current-collecting device comprising a rotatable Contact member, a plurality of brush members co-operating therewith, a common conducting supporting member, studs 011 said supporting member conductive ly supporting said brush members, and a closed-circuit magnetizable conducting member enclosing said supporting member between two adjacent studs for offering an im pedance to the flow of variable currents through said supporting member from one of said studs to the other.

9. A current-collecting device comprising a slip ring, a plurality of sets of one or more brushes bearing thereon, a common non-magnetic conducting supporting member, means for conductively mounting said brushes on said supporting member, a magnetizable member associated with said supporting member between adjacent sets of brushes, whereby said supporting member is divided into a plurality of non-magnetic sect-ions, and a plurality of conductors connecting said sections in parallel.

In testimony whereof, I have hereunto subscribed my name this 28th day of June 1922.

CHARLES F. WAGNER. 

